According to a study by Huang et al published in March 2018’s Scientific Reports, almost 25% of eyes examined for cataract surgery have macular pathologies that do not show up on clinical examinations. Because OCT can be used to identify macular pathologies like epiretinal membrane (ERM), vitreomacular traction (VMT) and others, it makes an impact on cataract surgeons’ decision-making and supplementing the clinical examination. In short, there is value in information; it drives clinical decisions and patient education prior to surgery.
DIAGNOSTIC PROTOCOL FOR PRESURGICAL TESTING
My presurgical testing for all cataract patients consists of non-contact biometry (IOLMaster 700, Carl Zeiss Meditec) measurements of the length of the eye to determine the power of the IOL as well as keratometry readings (ARK, Nidek) to measure the curvature of the cornea. I also perform manual keratometry on some patients who have a significant amount of corneal astigmatism as an additional measurement of the corneal cylinder. In addition, I perform a preliminary macular OCT on all of my cataract surgery patients as well as a topography on the cornea.
PATIENT MEDICAL HISTORY’S INFLUENCE ON OCT
Most doctors who do not perform a preliminary macular OCT on their patients may look to medical history for certain diseases, such as diabetes or hypertension, to prompt them to investigate potential macular pathology. They can be fooled into thinking that their view into the eye through a fairly dense cataract is sufficient to evaluate the macula.
I have examined patients with no history of disease or obvious visual evidence of macular pathology due to a dense cataract that obscures the view of the retina. However, following imaging with an OCT, I have discovered macular pathology that I did not know existed. This has prompted me to take OCT images of patients with no known history of disease.
ADDRESSING THE PATHOLOGIES
When I identify macular pathologies like an ERM or VMT, I can address those concerns prior to cataract surgery. When I find pathology, I refer the patient to a retina specialist to evaluate the findings. If the pathology needs treatment, such as a choroidal neovascular membrane from macular degeneration, the retina specialist can properly diagnose the findings on the OCT and offer the appropriate treatment.
Preoperative identification of any retinal pathology and their possible impact can be explained to the patient. For example, on a preoperative exam for a 55-year-old man who developed cataracts, the macular OCT revealed VMT. This allowed us to discuss this asymptomatic finding before surgery and the risks of development of a macular hole or edema after surgery.
The OCT’s graphic display allows me to show images to my patients to explain their retinal pathology, including side-by-side comparison of images of the patient’s eye and a healthy eye. Even when a patient does not understand the exact layers of the retina, he or she understands the difference between a normal and abnormal picture.
This education helps patients to understand the abnormal finding and that it might affect the outcome of the surgery. This additional imaging by the OCT helps facilitate the discussion about IOL options.
IMPACT ON ADOPTION RATES
Using OCT prior to cataract surgery has increased my adoption rates for multifocal/presbyopia-correcting lenses. I feel more confident and comfortable in my preoperative evaluation of the patient. This increases my confidence when recommending these lenses, because I am sure the patient’s eye is healthy. Alternatively, if the view into the eye is unclear because of corneal opacities or the lens, I may feel less confident that I am seeing the full health of the eye.
Knowing the full health of the eye gives confidence to patients, because they understand that their maculae are healthy and I have thoroughly evaluated the eye. If a significant pathology is present, the patient understands why it may be too risky to implant a lens technology that might decrease his or her contrast sensitivity.
FACTORING IN THE COST
Obtaining an OCT before surgery to evaluate the retina is part of my normal workup. I do not bill for these images. If the practice already has an OCT, the only significant cost of obtaining an OCT image comes from printing the results. However, if the OCT image can be viewed digitally or on the machine itself, there is no additional cost. The personnel cost is minimal if the technicians who capture the test are already employed by the practice and already present for other responsibilities.
Preoperative macular OCT should be performed for all cataract surgery patients to evaluate visual outcomes — from routine patients to myopic patients and those considering advanced-technology IOLs. OM